lauckert



No. 608,878. Patented Aug. 9, I898. E. F. H. H. LAUCKERT.

SWITCH FOR VABYING ELECTRICAL RESISTANCE.

(Application filed Nov. 29. 1897.) (No Model.) 2 Sheets$heetl M85338. XM

No. 608,878. Patented Aug. 9, I898. E. F. H. H. LAUCKERT.

SWITCH FOR VARYING ELECTRICAL RESISTANCE.

(Application filed Nov. 29, 1897.)

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UNITED STATES PATENT OFFICE.

EDUARD F. II. II. LAUOKERT, OF LONDON, ENGLAND, ASSIGNOR TO SIEMENS BROTHERS & CO., LIMITED, OF SAME PLACE.

SWITCHFOR VARYING ELECTRICAL RESISTANCE.

SPECIFICATION forming part of Letters Patent No. 608,878, dated August 9, 1898.

Application filed November 29, 1897, Serial No. 560,147. (No model.) Patented in England May 2, 1895, Not 8,727.

T0 (1, whom it may concern.-

Be it known that I, EDUARD FRIEDRICH HERMANN HEINRICH LAUCKERT, of 12 Queen Annes Gate, lVestminster, London, in the county of Middlesex, England, have invented certain new and useful Improvements in Switches for Varying Electrical Resistance, (for which I have obtained a patent in Eng land, No. 8,727, dated May 2, 1895,) of which the following is a specification.

For many purposes, especially for the starting and regulating of motors,it is necessary to vary the resistance in an electric circuit, and in order to effect this gradually there are arranged in a switch a considerable number of contact plates or segments connected through successive resistances and a brush or rubber which is moved over these so as to introduce or cut out these resistances step by step.

This invention relates to the construction of resistance-switches and their brushes in such a manner that in order to provide for a given number of steps the number of contact plates or segments and of the resistances and their connections may be considerably reduced, or, in other words, that a given number of plates or segments, resistances, and connections may serve. for a considcrablygreater number of steps. For this purpose instead of one brush two or more brushes insulated from each other are employed. One of these, which may be termed the leading brush, as it is moved over the contact plates or segments brings them successively into direct connection with the circuit. The second brush as it is moved along with the first brings the successive plates or segments into connection with a bar or segment which is connected not directly but through a certain resistance to the circuit.

In like manner there may be a third brush moving along with the others and connecting the successive plates or segments to another bar or segment connected to the circuit through another resistance. The successive contact plates or segments may be so spaced that only one of the brushes is 011 one of them at a time. When the first brush is on, all the resistance up to that particular plateor segment is in circuit. When the second brush is on, an additional resistance is included, and

when the third brush is on a still greater resistance is included. In this way the added resistance due to the step from one contact to the next is divided into three steps, or a certain number of contact-plates and resistances is by the addition of the two brushes and their two resistances rendered available for thrice the number of steps.

According to a modified arrangement the leading brush is connected to each of the others through a resistance. The contact plates or segments are so arranged that one, two,0r all of the brushes maybe 011 one plate or segment at a time or that one,two,or more may be on one plate,while of the others one may be over the gap between the plates and the others on the n ext plate. By the parallel routes thus provided for the current the step from one re sistance to the next in order is subdivided.

In cases where the successive resistances between the plates or segments vary it may be of advantage also to vary the resistances between the leading brush. and the others. This can be done by providing each of the brushes with a second contact sliding over a separate conducting bar or segment, which may be divided into sections connected to each other through suitable resistances.

Figure 1 is a diagram showing a series of resistances and contact-segments constituting a switch with twobrushes 1 and 2,insulated from each other, except that they bear on conducting-bars10 and 13, connected together through a resistance 4:. Then the brushes are in position A, the current to be varied in the circuit 8 passes at 9 to the first segment 6 through brush 1 and bar 10 back to 8. By moving the brushes to a position such as B, when the brushes are on two segments, the current, entering at 9 and passing through a number of resistances 7 to the point 11,divides into two parts, one passing through'resistance 12 and brush 1 to the bar 10 and the other part pass ing by brush 2, bar 13, and resistance 4: to bar 10, Where it joins the first part, both return" ing together to 8. By moving the brushes to such a position as (J, where brush 2 is over the interval between two segments, the cincuit-bar 13 and resistance 4 is cut off. At position D of the brushes the current, after having passed through all resistances 7 ,passes through the brush 2, bar 13, resistance 4, and bar 10 to 8.

Fig. 2 is a diagram of a switch with three brushes. In position A the current passing by 6, 1, and 10 encounters none of the resistances. In position B brush '1 is on one segment and brushes 2 and 3 on the preceding segment, putting three resistances 4, 5, and 7 in parallel. In position brush 1 is on one segment, brush 2 is over an interval, and brush 3 is on the preceding segment. In this case resistance 4 is disconnected and only 5 and7 are in parallel. In position D the brushes 1 and 2 are on one segment and brush 3 is over a gap, the resistance 7 being only in circuit.

Figs. 3 and 4 are diagrams of switches in which the resistance-steps 7 are increased as more resistance is introduced into the circuit. The resistances between the brushes must also increase, and therefore the conductingbar 13 in Fig. 3 and the bars 14 and 15 in Fig. 4 are made each in two parts, with resistances 16 connecting the parts, which in positions of the brushes at and beyond G are added to the resistances 4 and 5.

In Figs. 1, 2, 3, and 4 the contacts and bar are shown arranged for rectilineally-sliding brushes. They may be conveniently arranged for brushes moving circularly.

Fig. 5 is a section, and Fig. 6 a plan,of such a circular switch having thirteen contact-segments S, with interposed resistances T, which I with a single brush in the usual way would The brush A is in connection through the axis with terminal D. The brush 13 moves over the conductingsegments 0, one segfl mcnt of which is connected to brush A through I a resistance E. There are three intervals between the segments 0, bridged by resistances F G H, so that as the back part of brush B slides over the segments the resistances]? G II are automatically added to the resistance E. W'hen the brushes are in the position shown in Fig. 6, all the resistances 'l, E, F, G, and II are in circuit.

at K, passes through the twelve resistances T to brush B and the segment C, then through The current enters ance,the combination with a series of conducting segments connected by successive resistances, of two or more brushes connected to move together but insulated from each other and electrically connected through a resistance, and designed to be moved over said conducting-segments and in contact therewith, one or more of said brushes being of a width to lie over the interval between two segments and out of contact with either, substantially as described.

2. In a switch for varying electrical resistance, the combination with a series of conducting-segments connected by successive resistances, of two or more conducting-bars connected by resistances, andtwo or more brushes connected to but insulated from each other and bearing respectively on said conducting-bars, said brushes being designed to be moved over said conducting-segments and in contact therewith and one or more of said brushes being of a width to lie over the interval between two segments and out of contact with either, substantially as described.

3. In a switch for varying electrical resistance, the combination with a series of conducting-segments connected by successive resistances, of two or more conducting-bars connected by resistances, one or more of said bars being formed in two parts connected by a resistance, and two or more brushes connected to but insulated from each other and bearing respectively on said conducting-bars, said brushes being designed to be moved over said conducting-segments and in contact therewith and one or more of said brushes being of a width to lie over the interval between two segments and out of contact with either, substantially as described.

In testimony whereof I have signed my name to this specification, in the presence of two subscribing witnesses, this 16th day of November, A. D. 1897.

EDUARD F. H. II. LAUOKERT.

Witnesses:

JNO. P. M. MILLARD, OLIVER IMRAY.

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